2652-65-5Relevant academic research and scientific papers
Photochemistry of 9-fluorenone oxime phenylglyoxylate: A combined TRIR, TREPR and ab initio study
Kolano, Christoph,Bucher, Goetz,Wenk, Hans Henning,Jaeger, Martin,Schade, Olaf,Sander, Wolfram
, p. 207 - 214 (2004)
The photochemistry of 9-fluorenone oxime phenylglyoxylate (1) in tetrachloromethane was investigated by a variety of time-resolved methods [STEP-SCAN TRIR and time-resolved EPR (TREPR)]. Photolysis of 1 yields the benzoyl radical, carbon dioxide and the f
ABSOLUTE RATE CONSTANTS FOR HYDROGEN ABSTRACTION FROM ALDEHYDES AND CONFORMATIONAL STUDIES OF THE CORRESPONDING AROMATIC ACYL RADICALS
Chatgilialoglu, C.,Lunazzi, L.,Macciantelli, D.,Placucci, G.
, p. 5252 - 5256 (1984)
Absolute rate constants for the reactions of tert-butoxyl radicals with some organic aldehydes have been measured in solution by using laser flash photolysis techniques.At 297 K, the rate constants are 8.9, 6.8, 1.0, and 0.05*1E7 M-1 s-1 for EtCHO, C6H5CHO, Me2NCHO, and EtOCHO, respectively.Arrhenius parameters were determined for benzaldehyde.Polar effects are very important in determining the reactivity of organic aldehydes toward tert-butoxyl radicals.The EPR spectra are described for a number of furoyl, thenoyl, and pyrroyl radicals (ArC*O) which were generated photolycally over a wide range of temperatures.Conformational isomers were detected and their structural assignment obtained from the magnitude of the hyperfine splittings of the ring protons, by comparison with the conformers of the parent aldehydes, and from the solvent dependence.
First unequivocal identification of the critical acyl radicals from the anti-tuberculosis drug isoniazid and its hydrazide analogs by complementary applications of ESR spin-trapping and HPLC/MS methods
Huang, Chun-Hua,Mao, Li,Qin, Li,Shao, Bo,Zhu, Ben-Zhan
, p. 1 - 8 (2020)
The carbon-centered isonicotinic acyl radical of isoniazid (INH), a widely-used frontline anti-tuberculosis drug, has been considered to play a critical role in inhibiting Mycobacterium tuberculosis, but not fully identified. Here we show that this radical intermediate can be unequivocally characterized by complementary applications of ESR spin-trapping and HPLC/MS methods by employing N-tert-butyl-α-phenylnitrone (PBN) as the suitable spin-trapping agent, which can form the most stable radical adduct. More importantly, for the first time, analogous carbon-centered acyl radicals and their respective NAD+ adducts have also been detected and identified from its two isomers (nicotinic acid hydrazide and 2-pyridinecarbohydrazide) and benzhydrazide which are structurally-related to INH, but not by 2-chloroisonicotinohydrazide. This study represents the first unequivocal identification of the carbon-centered acyl radicals of INH and other hydrazide analogs by both ESR spin-trapping and HPLC/MS methods, which may have broad biomedical and toxicological significance for future research for more efficient hydrazide anti-tuberculosis drugs.
NIR Light-Induced ATRP for Synthesis of Block Copolymers Comprising UV-Absorbing Moieties
Kütahya, Ceren,Meckbach, Nicolai,Strehmel, Veronika,Gutmann, Jochen S.,Strehmel, Bernd
, p. 10444 - 10451 (2020)
NIR exposure at 790 nm activated photopolymerization of monomers comprising UV-absorbing moieties by using [CuII/(TPMA)]Br2 (TPMA=tris(2-pyridylmethyl)amine) in the ppm range and an alkyl bromide as initiator. Some of them comprised structural elements selected either from those showing proton transfer or photocycloaddition upon UV excitation. Polymers obtained comprise living end groups serving as macroinitiator for controlled synthesis of block copolymers with relatively narrow molecular weight distributions. Chromatographic results indicated formation of block copolymers produced by this synthetic approach. Free-radical polymerization of monomers pursued for comparison exhibited the expected broader dispersity of molecular weight compared to photo-ATRP. Polymerization of these monomers by UV photo-ATRP failed on the contrary to NIR photo-ATRP demonstrating the UV-filter function of the monomers. This work conclusively provides a new approach for the polymerization of monomers comprising UV-absorbing moieties through photo-ATRP in the NIR region. This occurred in a simple and efficient pathway. However, studies also showed that not all monomers chosen successfully proceeded in the NIR photo-ATRP protocol.
Gas-Phase Reactions of Phenyl Radicals with Aromatic Molecules
Fahr, Askar,Stein, S. E.
, p. 4951 - 4955 (1988)
Relative rates of reactions of phenyl radicals with a series of aromatic and polycyclic aromatic compounds are reported.Most studies were done in static reactors at 450 deg C using diphenyl diketone (benzil) as the phenyl radical source.Reactions with the following molecules are reported: benzene, toluene, p-xylene, 1,3,5-trimethylbenzene, phenol, bromobenzene, naphthalene, biphenyl, anthracene, 9-methylanthracene, and triphenylene.For reactions with substituted benzenes, H abstraction is the dominant reaction.Relative rates of phenylation at different sites do not closely follow established trends for rates of radical attack.It is proposed that these deviations are primarily due to a dependence of the degree of reversibility on the specific site of phenylation.These studies also show that the rates of phenyl and H-atom migration around the ring in adduct radicals are slow relative to dissociation.Also, by use of these results to link literature rate data from high and low temperatures, a rate expression for H abstraction from p-xylene by phenyl of 109.6 exp(-4.4 kcal/RT) M-1 s-1 is derived.
Photogeneration and reactivity of acyl nitroso compounds
Evans, Anthony S.,Cohen, Andrew D.,Gurard-Levin, Zachary A.,Kebede, Naod,Celius, Tevye C.,Miceli, Alexander P.,Toscano, John P.
scheme or table, p. 130 - 138 (2011/04/23)
Acyl nitroso compounds have been generated by photolysis of several different classes of precursors including 9,10-dimethylanthracene adducts, nitrodiazo compounds, and 1,2,4-oxadiazole-4-oxides. Consideration of the nitronate-like resonance structure of nitrodiazo compounds led to an examination of the photochemistry of nitronates with -leaving groups. Photolysis of such nitronates has been shown to generate an acyl nitroso species along with a carbene intermediate. Nanosecond time-resolved infrared (TRIR) spectroscopy has been used to detect photogenerated acyl nitroso compounds directly and to examine their reaction kinetics with amines and thiols. The mechanism of acyl nitroso aminolysis by primary amines involves general base catalysis, while the mechanism of aminolysis by secondary amines is strictly bimolecular. Thiols do not seem to be reactive with acyl nitroso compounds on the microsecond time scale, but thiolates are quite reactive. The reaction between benzoyl nitroside and an organic-soluble thiolate, tetrabutylammonium dodecanethiolate, proceeds via a proposed tetrahedral intermediate, which is observable by TRIR spectroscopy.
Synthesis and characterization of cyclohexene oxide functional polystyrene macromonomers by ATRP and their use in photoinitiated cationic polymerization
Degirmenci, Mustafa,Izgin, Oner,Acikses, Aslisah,Genli, Nasrettin
scheme or table, p. 28 - 34 (2011/12/16)
In this study, a novel well-defined macromonomer of epoxy end-functionalized polystyrene was synthesized by atom transfer radical polymerization (ATRP). The compound 3-cyclohexenylmethyl-2-bromopropanoate was synthesized by the condensation of 3-cyclohexe
Effect of nitroxide radicals on chemically induced dynamic electron polarization of spin-correlated radical pairs in aqueous micellar solutions of sodium dodecyl sulfate
Gorelik,Tarasov,Shakirov,Bagryanskaya
experimental part, p. 1416 - 1427 (2009/09/30)
The multispin systems consisting of spin-correlated radical pairs (SCRPs) and stable nitroxide radicals, localized in micelles of sodium dodecyl sulfate (SDS), were studied by ESR and pulse laser photolysis techniques. In all the systems studied, the stab
Kinetic study of the hydrogen abstraction reaction of the benzotriazole-N-oxyl radical (BTNO) with H-donor substrates
Brandi, Paolo,Galli, Carlo,Gentili, Patrizia
, p. 9521 - 9528 (2007/10/03)
The aminoxyl radical (>N-O.) BTNO (benzotriazole-N-oxyl) has been generated by the oxidation of 1-hydroxybenzotriazole (HBT; >N-OH) with a CeIV salt in MeCN. BTNO presents a broad absorption band with λmax 474 nm and e 184
Kinetic Study of the Phthalimide N-Oxyl Radical in Acetic Acid. Hydrogen Abstraction from Substituted Toluenes, Benzaldehydes, and Benzyl Alcohols
Koshino, Nobuyoshi,Saha, Basudeb,Espenson, James H.
, p. 9364 - 9370 (2007/10/03)
The phthalimide N-oxyl (PINO) radical was generated by the oxidation of N-hydroxyphthalimide (NHPI) with Pb(OAc)4 in acetic acid. The molar absorptivity of PINO. is 1.36 × 103 L mol -1 cm-1 at λmax 382 nm. The PINO radical decomposes slowly with a second-order rate constant of 0.6 ± 0.1 L mol-1 s-1 at 25°C. The reactions of PINO . with substituted toluenes, benzaldehydes, and benzyl alcohols were investigated under an argon atmosphere. The second-order rate constants were correlated by means of a Hammett analysis. The reactions with toluenes and benzyl alcohols have better correlations with σ+ (ρ = -1.3 and -0.41), and the reaction with benzaldehydes correlates better with σ (ρ = -0.91). The kinetic isotope effect was also studied and significantly large values of kH/kD were obtained: 25.0 (p-xylene), 27. 1 (toluene), 27.5 (benzaldehyde), and 16.9 (benzyl alcohol) at 25°C. From the Arrhenius plot for the reactions with p-xylene and p-xylene-d10, the difference of the activation energies, EaD - E aH, was 12.6 ± 0.8 kJ mol-1 and the ratio of preexponential factors, AH/AD, was 0.17 ± 0.05. These findings indicate that quantum mechanical tunneling plays an important role in these reactions.
